Selvala, Eager Trailblazer (231) [Outlaws of Thunder Junction]

Vigilance Whenever you cast a creature spell, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery." {T}: Choose a color. Add one mana of that color for each different power among creatures you control.